Logic....
The person diving for the ball in desperation is in no position to make an accurate call.
The person on the other side of the net is clear sighted, he hit that short ball, is watching unimpeded, and is not moving around.
Now rules might say otherwise, but who should make this call?
We know the hitter wants to win the point.
We know the dropshotter wants to win the point.
Who has the better line of sight?